Lithosphere PPQs

What is an igneous process?

A process by which rocks and minerals are created by the cooling and hardening of magma or molten lava

What is a metamorphic process?

A process by which igneous processes or tectonic plate movements can alter existing rocks with high temperature and pressure, without melting them

What is a sedimentary process?

A process by which minerals settle and build up to produce layers of deposited sediment

Give two examples of metamorphic processes

Limestone becoming marble, mudstone becoming slate

What metal ores are deposited by hydrothermal deposition?

Tin, copper, lead, silver, gold and arsenic

What is Lasky's principle?

As the purity of a mineral decreases, the amount of mineral present increases exponentially

What is the stock/resource base?

All of the material that exists in the lithosphere that can be exploited now, will be exploitable when prices rise or when new technologies are developed

What is the resource?

All the material that is theoretically available for exploitation, includes deposits that can be exploited now and deposits that can be exploited when prices rise or new technologies are developed in the future.

What is the reserve?

The material that can be exploited now, economically, using existing technology

Describe IR spectroscopy

Different materials emit infrared radiation as different wavelengths and these can be used to identify them

Describe gravimetry

Gravimeters detect variations in gravity caused by variations in density and mass

Describe magnetometry

Magnetometers detect rocks that are magnetic, e.g. magnetite

Describe seismic surveys

Sound waves are produced by controlled explosions or a seismic vibrator on the surface, the echoes can give information on the depth, density and shape of the rock strata

Describe resistivity

The measurement of the difficulty of which electricity passes through a material

Describe trial drilling

Produces samples of the rocks underground, most expensive technique

What factors affect mining viability?

Ore purity

Chemical form of the mineral

Overburden hardness and depth

Hydrology

Cut-off ore grade

Transport costs

Market economics

How does ore purity affect mining viability?

If the purity is low then more rock will have to be mined, more spoil will be produced, more energy will be needed for processing and mining, more pollution will be generated

How does hydrology affect mining viability?

Higher precipitation or impermeable rocks below increase drainage costs

How does depth affect mining viability?

Costs increases as depth increases

The sides of the mine cannot be vertical because of the risk of collapse so the amount of rock that needs to be removed increases

As depth increases, the amount of water that flows into the mine from surface runoff or groundwater also rises, increasing pumping costs significantly

What are the factors that affect transport cost?

Distance to market, the ease of bulk transport, the presence of suitable existing transport infrastructure and whether the bulk of the mineral has be reduced by processing

What are the environmental impacts of mining?

Land loss for other uses

Habitat loss

Loss of aesthetics

Dust

Noise

Turbid drainage water

Spoil disposal

Mine site restoration

Unstable spoil heaps

Acid mine leachate

How may acid mine leachate be controlled?

Pass through a filter bed of crushed limestone to immobilise metals and prevent them from being carried into rivers

How may unstable spoil heaps be controlled?

Landscaping to reduce gradients

Adding soil, nutrients and planting vegetation

Spoil heap drainage

How can turbid drainage water be controlled?

Sedimentation lagoons

How can noise pollution be controlled?

Embankments and baffle mounds

Blasting at set times of day and restricting blasting to daytime only

How can dust pollution be controlled?

Water sprays

What is bioleaching?

The use of living organisms to extract metals from their ores. The metals in the solution produced can be separated by electrolysis or using carbon filters

Explain why a reduction in the market price for tin would change the ‘cut-off ore grade’.

There would be an increased COOG because a lower market price means less money available for extraction and processing

Give one reason why the energy required for extraction increases as the ore grade declines.

Increased amount of ore must be mined/processed

Increased amount of overburden must be removed

Reduced efficiency of extraction – (residual mineral is greater proportion of the mineral present)

Explain how one property of a named mineral resource or mineral group may make it possible to detect its presence with a geophysical technique

Magnetism of iron ore or magnetite - Magnetometry

High density of igneous deposits - Gravimetry

High electrical resistance of igneous deposits – Resistivity

How is coal formed (igneous, sedimentary alluvial, sedimentary biological, sedimentary evaporite or metamorphic)?

Sedimentary biological

How is halite/sodium chloride salt formed (igneous, sedimentary alluvial, sedimentary biological, sedimentary evaporite or metamorphic)?

Sedimentary evaporite

How is slate formed (igneous, sedimentary alluvial, sedimentary biological, sedimentary evaporite or metamorphic)?

Metamorphic

How is hydrothermal copper ore formed (igneous, sedimentary alluvial, sedimentary biological, sedimentary evaporite or metamorphic)?

Igneous

How is gravel formed (igneous, sedimentary alluvial, sedimentary biological, sedimentary evaporite or metamorphic)?

Sedimentary alluvial

Name a major use of limestone

Building construction

What is the formation process of limestone?

Sedimentation

What is a major use of sand?

Glass

 

What is the formation process of granite?

What is the formation process of halite/sodium chloride salt?

Marine sediments

Describe the processes that produce hydrothermal metal mineral deposits

Groundwater is superheated

Hot groundwater dissolves the minerals in the rock

A mineral rich solution forms and travels up through the hydrothermal vents

As the water moves up it loses temperature and pressure

As the mineral solution cools, minerals crystallise out in order of their solubility

Outline how an assessment in the viability of a mine requires information about the mineral deposits

Chemical form

Ore purity

Ore body area

Ore body shape

Quantity

 

Outline how an assessment in the viability of a mine requires information about the associated geological structures

Explain the meaning of resource in terms of quantity and viability of exploitation

All materials that are known or thought to exist that can be now or in the future with future technology

Explain the meaning of reserve in terms of quantity and viability of exploitation

What can be profitably mined under current conditions

How would the cut off ore grade change if the market prices rise?

It would decrease

Outline one way that improved technology may be used to exploit low grade ores

Phytomining – plants absorb metal minerals, once incinerated the heavy metals can be collected from the ash

Outline one method that may be used to measure the pH of the drainage water from a mine spoil heap

Use universal indicator paper, red – acid, green – neutral, blue – alkaline

pH meter with calibration

Describe one named remote sensing method that may be used to find areas where trial drilling may be carried out

Seismic surveys – create soundwaves at the surface which pass through the rock and reflect back, detecting rock depth and density

Explain why the exploitation of low grade ore may increase the environmental damage cause by mineral exploitation

More rock must be mined

More habitat loss

More overburden

More ore extracted

More energy used

More pollution produced

How does the resource of a mineral differ from its reserves?

The resource is the theoretical materials that can be extracted now or in the future, Reserve is what you can profitably mine now

Suggest one reason why the energy used for extraction increases as the ore grade declines

More rocks must be mined and processed

Describe one method that is used to extract metals from low grade ones

Electrolysis after leachate collection

Exploratory drilling to search for new deposits is very expensive

Describe one method that is used to find the areas where drilling may be worthwhile

Seismic surveys – detect rock density and depth, soundwaves are produced at the surface, pass through the rock and reflect back

Suggest why an increase in the market price may change the cut-off ore grade of a mineral

The COOG decreases because more money can be spent on extraction, and lower grade ores can be exploited

Outline the advantages and disadvantages of using satellite surveying techniques rather than ground-based surveys

Advantages – cost effective, less labour intensive, lower habitat impact

Disadvantages – less information given, no physical rock to analyse, high initial cost, less sub-surface information

Describe one method of exploiting minerals from low grade ore deposits

Phyto mining - incineration

Leachate – electrolysis

Bioleaching – add acidophilic fungi or bacteria to make the rock acidic, metals become soluble and leachate dribbles out

Use one example to describe how material substitution may be used to conserve the reserves of metal minerals

Copper cables can be replaced with plastic

Copper pipes can be replaced with plastic

Steel car panels can be replaced with plastic

Copper electricity cables can be replaced with aluminium

Describe a method that may be used to extend the operation of a mine by exploiting low grade ores

Leachate collection can be done via electrolysis

Large scale mechanisation is cheaper

Explain why the exploitation of low grade ores is likely to affect the energy required to extract the metal

As ore purity increases, processing needed increases, so more energy is needed

As the demand for minerals increases, new deposits must be found and mines developed

Outline two features of a mine that may affect its viability

Overburden depth – more has to be removed if it's deeper

Overburden hardness – more difficult to remove if it's harder

Overburden stability – more is removed if looser

Mine drainage – high pumping cost if it has poor drainage

Outline how a change in the economy may cause the cut-off ore grade of a mineral to change

If the market price increases, the COOG lowers

Outline methods that may be used to reduce the environmental problems caused by machinery noise

Sound baffles

Restrict working hours

Outline methods that may be used to reduce the environmental problems caused by dust

Water sprays

Afforestation

Outline two ways in which open cast-mining causes more environmental damage than deep mining

More spoil heaps – more landslides and more erosion

More overburden removed – more waste disposal

More surface disturbance – more habitat loss

Describe one method that may be used to measure the pH of mine drainage water

Colour comparison of universal indicator paper

Outline two features of the overburden above the mineral that can affect the viability of the mine

Hard – difficult to mine

Loose – more removed

Depth – increased cost

Outline two methods of reducing environmental problems caused by mine machinery

Use water sprays to reduce dust pollution

Quieter transport, e.g. rails replace lorries

Time of traffic – avoid sensitive times

Afforestation to deflect noise

One method used in spoil heap reclamation is the addition of soil followed by tree planting. The soil must have the right texture to reduce the risk of soil erosion.

Outline a method used to estimate the proportions of sand, silt and clay in a soil sample

Dry the sample, sieve it and then weigh it

Figure 3 shows a cross section of a granite batholith and its associated geological structures 

Explain how hydrothermal processes produced economically recoverable metal ore deposits

Hot mineral solutions flow along fissures, away from batholith 

Different minerals have different solubilities 

Mineral solutions cool with movement away from source 

Minerals separated by deposition at different positions

The table shows the market price of copper on selected dates 

(Prices adjusted to April 2007 value) 

Explain why the cut-off ore grade was highest in June 1999 

A greater purity is needed for profit as it has the lowest market price

The table shows the market price of copper on selected dates 

(Prices adjusted to April 2007 value) 

Explain why the market price in May 2006 caused the estimates of reserves to increase

Low grade ore becomes economic and profitable